In the industrial practice of electric power systems, it is necessary to constantly monitor the operating state of a synchronous motor, so as to ensure the synchronous motor to operate in an optimum state. At present, an electric power system generally adopts, at operating locales, various types of meters to display the current, voltage, power and other related electric data of the synchronous motor, especially adopts a power angle meter to measure the power angle and other related electric data of the synchronous motor, and displays the electric power angle vector graph of the synchronous motor through a TV screen (as shown in FIGS. 6 and 15), so as to provide intuitional electric vector graph for operators.
However, there are disadvantages in various electric measuring meters currently in use. For example, the defects of the power angle meter which is capable of displaying the electric data and electric vector graph of a salient-pole synchronous motor are:
1. The power angle meter can only display the electric power angle vector graph of the synchronous motor (as shown in FIG. 6), but it cannot directly display the mechanical relationship between the stator and the rotor of the synchronous motor.
2. Although the power angle meter can display the electric power angle vector graph of the synchronous motor and reflect the stator armature potential, magnetic excitation potential, motor-end voltage, power angle and other electric data of the synchronous motor, it cannot display, with optimum segments, the magnitudes of active power and reactive power of the synchronous motor or the magnitudes of active components and reactive components of other parameters of the synchronous motor.
3. The power angle meter cannot satisfy the requirements of various professionals working in synchronous motor monitoring and operating. With the development of electric technology, a majority of dynamotor sets in the power plants realize the centralized control by programs. Compared with the number of other professionals, the number of electric professionals working in dynamotor monitoring and operating is less and less. However, it is difficult for non-electric professionals to understand the electric power angle vector graph displayed by the power angle meter of the synchronous motor.
4. The power angle meter cannot be applied to synchronous parallel-network monitoring of the synchronous motor.
5. The power angle meter cannot display the end magnetic leakage condition of the synchronous motor.